1. Field of the Invention
This invention relates generally to fueling systems for internal combustion engines and more particularly to air-intake metering and control of fuel quantity in proportion thereto and blending therewith comprising moveable elements in the confines of tubular conduit thereby yielding outputs applicable to fuel regulating devices for fuel-to-air proportioning control and fuel dispersion device in the air stream.
2. Description of the Prior Art
Prior art relating to the metering of air flow by mechanical air flow sensors utilized in fuel injection systems for spark ignition internal combustion engines in automotive application for control of fuel quantity in optimum ratio thereto have been of two principal types.
The major components of one such system are the pivotally arranged baffle plate in an air Venturi, whose movements actuate the control piston of a fuel quantity and distributing valve to fuel injectors.
The major components of another type system are "an air flow sensor flap", in essence a pivoting vane in a "measuring duct" section together with a "compensation flap" an integral part of the sensor flap in a chamber aside from the airflow path. Both devices have flat plane upstream surfaces that measure the force of the impinging air stream by the counteracting force of a "return spring" or the control pressure force of a fuel control valve.
A flat baffle plate in a Venturi intake tube is the metering sensor of the Mercedes-Benz Continuous Injection System (CIS), and the Bosch K-Jetronic fuel injection system.
The pivoting vane and flap are transduced to electric switching and signal to microprocessor control of solenoid operated injectors constituting the air flow sensor of the Bosch L-Jetronic fuel injection system.
In both systems, the use of a flat surface of a baffle plate or vane reacting to impinging air flow conditions requires empirical solutions and auxiliary systems for the effects of turbulence and non-linear outputs at a steady state of flow conditions and particularly during transitional conditions of acceleration and deceleration by throttle control of airflow. This causes fluctuation and oscillation from the effects of differential pressure on the relatively large flow impeding surfaces before and after airflow is accelerated or retarded to the steady state condition.
Also in use are electronic meters such as "hot wire" and "sonic" sensing for operation in conjunction with microprocessors in systems designated as Electronic Fuel Injection (EFI).
All such metering systems presently in use for "fuel injection" systems are in conjunction with devices or systems for control of fuel quantity by controlling fuel pressure to pressure-atomizing injectors (continuous injection) and for intermittent discharge of electric injectors under constant fuel pressure (Electronic Fuel Injection both systems injecting into intake valve passages of individual cylinders (ported injection).
Certain U.S. patents of applicant disclose the new "variable Venturi" structure technology wherein an element of the structure being a member movably supported in a tubular casing through which a fluid is caused to flow around and through said member, said member being contoured and streamlined, the forces engendered by said fluid flow on said member are governed by the laws and principles of fluid dynamics and similar to those of aerodynamics for atmospheric air.
When the moveable element of such structure is encompassed by an air stream and constrained to non-turbulent streamlined flow through Venturi-like passages, the force imposed by said air stream on such element urges such member downstream. When downstream movement by such force is opposed by a counterforce such as a spring of linear tension the extent of displacement of the moveable member and the magnitude of countervailing force are outputs proportional to the mass-volume of air flow.
The contouring of such confined streamlined members to form Venturi-Like passages which vary by said members movement also yields a differential air velocity pressure output taken from the varying throat section of such structures which differential-velocity pressure is proportionate to mass-volume of the prevailing air flow.
The referenced patents of this inventor disclose various shaped members which positioned in an air stream confined to a tubular duct which function as flow rate meters responsive to the aerodynamic force of the air stream on the structure's shaped members. The prevailing aerodynamic force being countervailed by a spring as the force storage device provides physical outputs that are a measure of air flow quantity. These outputs are: differential air pressure, called Venturi vacuum, the extent of displacement of the moveable element, and the magnitude of countervailing force, each of which are proportional to mass-volume of the air flow.
A system in accordance with the invention is applicable to spark-ignition internal combustion engines to proportion the ratio of combustion air to fuel, to maintain an optimum ratio thereof under varying conditions of load and speed throughout a wide operating range and for various systems of carburetion and fuel injection.
Although the structures of this invention provide the function of metering the air for control of fuel in optimum ratio thereto and having the capability of introducing the fuel into the metered air stream by a single continuous injector discharging into an interior passage of the moveable member, they also serve for proportioning fuel control in fuel injection systems that control fuel into cylinder air intake passages (ported injection).
Operational control of internal combustion engines in automotive operation is by means of an arbitrarily actuated throttle valve in an air intake casing of an air intake manifold. The air metering devices and the structures of the subject invention are in the intake casing upstream of the throttle valve and therefore subject to the pressure and velocity changes of the air flow that results from sudden or rapid throttle position change.
A body movably supported in a tubular casing, wherein an air stream is caused to flow therethrough encompassing the said body subjects the body to the following forces:
(a) impingement on the upstream projected surfaces by the change of direction of the stream flow. (F=MA).
(b) skin friction on the surfaces subjected to the flow.
The air stream flowing through a tubular casing that confines the moveable body in a passage surrounding same introduces additional forces occurring when throttle induced changes airflow from steady state conditions. These are:
(c) the instant static pressure differential across the moveable body acting on the body before a steady state of air flow and member movement pertains.
Non-streamline shaped bodies such as flat and angled plates because of the sharp directional change of the flow stream yields a considerable impingement force causing turbulent flow and frictional resistance such forces being without functional relationship to the mass-volume of flow requires empirical determinations to obtain a desirable result. Stream-lined shapes and Venturi-like passages of structures wherein laminar airflow conditions are emanated eliminates impingement force and turbulence leaving only skin-friction which is negligible whereas the Venturi-like surrounding air passage adds the forces which are a function of mass-volume of air flow over such shapes.
Change of the state of airflow by throttle manipulation in such structures causes an instant differential static pressure force across the moveable member whose magnitude is a function of the proportions of projected surface areas of the moveable member to the flow-through area of the air passage(s) and of the magnitude of the structure's inertia which delays response of the system to a steady state condition consistent with the new throttle position.
Application of fueling systems to automotive engines requires adapting air-fuel mixture to steady state conditions of load and speed, and to the transitional conditions of acceleration and deceleration.
Efficient and smooth response to operational transitions without auxiliary means are inherent in the fluidic metering structures as improved by this invention and their combination with fuel controlling devices and systems for automotive engines.